Synthesis and Characterization of New Potential Hypoxia-Sensitive Azo-thiacalix[4]arenes Derivatives

The subject of this article is new potential hypoxia-sensitive azo-thiacalix[4]arenes derivatives in the 1,3-alternate configuration. Previously, it was shown that azo derivatives of calix[4]arene in the cone conformation form complexes with rhodamine dyes. The present work is devoted to the synthesis of new azo derivatives using the thiacalix[4]arene platform. A new highly productive method for the synthesis of thiacalixarene with four anionic sulfonate azo fragments on the lower rim (compounds 2a–b) for further complexation with the most common cationic dyes is reported. The chemical structures of the products obtained were established based on 1H and 13C NMR, IR spectroscopy, MALDI TOF mass spectrometry, and elemental analysis